I have 2 neo 6m GPS modules, and one neo7. I thought they all had the same problem. they do, but not the problem I thought they had. they all lock up to GPS, give a 1 per second PPA pulse. the PPA pulse returns a nice bright shine from an external LED. if you connect TXD and RXD to LEDs, one provides a nice bright LED, the other a feeble glow. this is a 3.3 volt chip on a board with a regulator. you can feed it with 5 volts, but the TXD and RXD pins need 3.3. it can survive a 5 volt RXD input, but it only puts out 3.3 V from TXD. you need a logic level converter to see the output on an Arduino. the symptom is the feeble LED. TXD from the module connects to RXD on the Arduino, and vice versa. I rank this right up there with the malignant SOB from Ford Motor Company who put 1: 6MM X 28 threads per inch screw under the dash to hold the console in place. sick SOB probably still chuckles over the grief he caused with that.